Asymmetric Design for a High‐Performance Indoor Radiative Heating Fabric

Abstract

Keeping the human body in a thermal comfort is a necessity for our own biological balance. Actually, to create a suitable thermal envelop in indoor areas, there are two strategies: using air conditioning systems (HVAC) to cool or warm the indoor space and/or clothing to adjust the temperature around the human body. The first strategy is showing his limitation due to the considerable energy consumption. In European Union, the building sector uses more than 40% of total energy consumption. [1] More than 50% of this energy is dedicated only for space heating. [2] This huge energy consumption is a worrying contribution to global warming. [3] In that assessment, clothes play a key role in our life to satisfy the human body thermal comfort by providing cooling in hot environment or heating in cold one. However, traditional clothes have a very limited thermal insulation performance. Indeed, a sudden variation of the ambient temperature can impact subsequently the thermal comfort of the body. The development of new textiles able to manage the temperature of the human body over a wide range of indoor temperatures, without providing additional external energy, appears to be an urgent necessity.Recently, personal thermal management has been demonstrated to be an efficient solution to replace the traditional ways of heating or cooling. [4,5] At normal skin temperature of 34 °C, the human skin emits thermal infrared (IR) radiations with a maximum peak around the wavelength 9.6 µm. In sedentary state, the infrared radiation accounts more than 50% of the total body heat losses. [6] By controlling the emissivity, transmissivity, and reflectivity of human body IR radiation through textiles, the temperature in the space between the skin and the textile (microclimate) can be controlled.Although many efforts have been made in the scientific community to develop radiative thermal management textiles, it remains, to this day, a major challenge. Tong et al. proposed an infrared-transparent visible-opaque fabric (ITVOF) which ensures the dissipation of thermal radiation emitted by the human body directly to the environment. [7] Hsu et al. have experimentally demonstrated that a nanoporous polyethylene (nanoPE) film presents both high infrared transparency and visible opacity. [8] The nanoPE film is opaque to human eyes Improving radiative heating performance of textiles is becoming one of the most current research topics to reduce the energy consumption used to control the indoor areas temperature. In this work, the properties of a textile-based asymmetric design for radiative heating are studied both theoretically and experimentally, and its remarkable efficiency over a wide range of temperature is demonstrated. By sandwiching a thin metallic layer characterized by a high reflectivity in the mid-infrared (MIR) between two polyethylene (PE) membranes of same thickness, it is proposed to control the MIR emissivity of the structure by the introduction of SiO 2 nanoparticles (NPs) in one of the two PE membranes. By reversing the fabric sid...

Dual‐mode smart flipping materials and devices for thermal management

“…Due to thermal management capability, this membrane held great promise in revolutionizing the design of future functional textiles, offering new insights and possibilities. The dielectric NPs could be integrated into polymers matrix to achieve the cooling goal, Boutghatin et al [ 52 ] explored the concept of utilizing a metallic layer with high reflectivity within the MIR band. To create the structure, they strategically placed this layer between dual polyethylene (PE) layers, each with an equal thickness.…”

A numerical approach to evaluate the personal radiative thermal management of textiles part one: Mid-infrared transmittance, reflection and absorption

“…In the last 5 years, research in the field of radiative cooling has commonly used numerical simulation tools to predict the optical performance of materials [16][17][18][19][20][21][22]. This approach has an acceptable prediction accuracy and a potentially low cost at the same time.…”